Homicide Research Paper

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The central theme of the law of homicide is the unique value of human life. While danger to life is an element of many other crimes as well, the law of homicide focuses on it directly, by declaring criminal a wide range of conduct that actually causes a death. Because life is valued so highly, such conduct is prohibited much more generally than conduct causing other kinds of harm. Whereas the criminal law for the most part is concerned with intentional harms, criminal homicide includes not only intentional killing but also a broad range of conduct from which death results unintentionally.

Homicide is the killing of a human being by another human being. (Suicide, insofar as the criminal law deals with it, is treated separately.) A question occasionally arises whether a death satisfies this definition, either because it is not clear whether the victim was a ‘‘human being’’ for this purpose or because it is not clear whether another person’s conduct caused the death. Most often, the fact of homicide is not an issue. The difficult questions are whether the homicide is criminal or noncriminal and, if the first, in which category of criminal homicide it belongs.

The Homicide Victim as a Human Being

When homicide is the issue, the law makes no distinctions among human beings as victims. It is human life as such that is protected, and none of the criteria of worth by which we may classify persons for other purposes is material. Death is the more or less remote end for us all, but it is no less homicide that the life cut short would soon have ended anyway, because of age, ill health, or any other reason.

No question has arisen in any adjudicated case as to whether a living creature who is the victim of a homicide was a human being or belonged to some other species. A problem of definition sometimes arises because it is necessary to determine when, in the process of prenatal or postnatal development, life as a separate human being begins or when, in the process of dying, life as a human being ends. The usual rule is that the victim of a homicide must have been ‘‘born alive.’’ The older law required that the fetus have been fully separated from the mother and have a separate existence, including an independent circulatory system; it was sometimes also required that the umbilical cord have been cut. There has been some modification of the requirement of full separation, probably in recognition of the easier and safer conditions of ordinary childbirth. It is still generally the law that the victim must have been born alive, which means that there were signs of separate existence and that the birth was far enough advanced so that it would ordinarily have been completed successfully. The destruction of a fetus before it has reached this stage of development is covered by statutes dealing specifically with abortion or the killing of a fetus.

At the other end of a life, the availability of heroic medical techniques to sustain some of the body’s vital functions, including circulation and respiration, after other functions have stopped has raised the question of when life ends. The question may be critical if an organ transplant is contemplated, because it is homicide if a human being, however near death, is killed; a successful transplant requires that the organ be removed before necrosis of tissue sets in. There is scant law to answer the question. In ordinary cases, death is deemed to have occurred when there is absence of a heartbeat and respiration. It has also been urged that irreversible coma or cortical brain death, which involves destruction of the cognitive faculties, is enough to constitute legal death, even if circulatory and respiratory action continue.

Action Causing Death

If someone acts with the intention to kill another person and the death occurs as he intended, there is no difficulty in establishing that his conduct is the cause of death. If he acts without intending to kill or if he has such intent but the death occurs in an unanticipated way, it may not be obvious whether his conduct or some other contributing factor for which someone else or no one else is criminally responsible should be regarded as the cause of death. Efforts to define more precisely the element of causation in homicide have not taken the law beyond what the concept of causation itself conveys. The matter is left to the trier of fact, who must decide on the basis of common sense and ordinary experience whether to attribute causal responsibility.

Since homicide is constituted by a result rather than a particular kind of action, one can commit homicide by an omission or failure to act, if the omission is the cause of death. In many situations, more than one person has an opportunity to take action that would avert death; it would be an extravagant extension of the notion of causation to say that the failure of each caused the death. Furthermore, the criminal law does not generally impose a duty to aid another, even if aid would avoid serious injury to the other and could easily and safely be given. Accordingly, criminal liability for homicide based on an omission is limited to failure to perform an act that one is otherwise legally required to perform. Liability is not based only on a moral obligation, however plain, arising from the danger to life or any other circumstance.

The most common example of such liability is the death of a dependent child resulting from a parent’s failure to provide the ordinary care required by law. The relationship of marriage also imposes on each spouse a duty to care for the other that will sustain liability for homicide. Other relationships, like the employer-employee relationship or the ship’s captain-seaman relationship, may also provide a basis for liability; the increasing impersonality of such relationships makes liability doubtful if there is not also some other basis of liability. A legal duty to act may be prescribed by a statute or regulation or may arise from a specific contractual undertaking or a voluntary undertaking that places the other person in one’s care. Even if there was a legal duty to act, a death resulting from an omission is not a criminal homicide unless all the elements of the offense, discussed below, are also present. If a person’s omission to perform a legal duty was not intentional or negligent, we should probably not describe it as having caused the death; but in any case, in the absence of the required culpability, the omission would not constitute a crime. Convictions of manslaughter by omission are not as rare as convictions of murder by omission; the latter are not, however, unknown, the most common example being a parent’s failure to care for an infant who is intentionally left to die.

When the failure to perform a legal duty manifests the same culpability that establishes liability for an act that causes death, liability for the omission, if death results, is unproblematic. One whose grossly negligent failure to act causes a death is not less guilty than one whose grossly negligent act causes a death. Similarly, if a person’s legal duty to act has the effect that no one else will probably act in his place, his deliberate nonperformance with the intent to cause death is not very different from a deliberate act. It may not, however, always be possible to establish a close equivalence between acts and omissions. Doubts of this kind, if they arise, are resolved as part of the requirement that the omission in question be the cause of death.

The notion of causation is usually used disjunctively. Ordinarily, a conclusion that one person has killed another precludes a conclusion that another person’s separate conduct has brought about the same death. Provided that the element of causing the death of another is satisfied in each case, there is no rule prohibiting more than one person from being criminally liable for the same death. If both parents of a child, each acting independently, failed to give him adequate care and the child died as a result, they might both be guilty of homicide. Similarly, in theory two persons whose independent acts were each the cause of another’s death might both be liable.

Most American jurisdictions have preserved a common law rule that a person cannot be convicted of homicide unless the death occurs within a year and a day after the conduct alleged to have caused the death. The purpose of the rule is to avoid a conviction if the passage of time has rendered the element of causation uncertain. Taking account of advances in medical science, the Model Penal Code and the law of some states have abandoned the rule.

Noncriminal And Criminal Homicide

Despite the value of life, the law recognizes that in some circumstances other values prevail. The official carrying out of a sentence of death, for example, is a deliberate, carefully planned homicide pursuant to the authority of the state. Killing an enemy in battle during war is another example of justifiable homicide, which the state not only permits but approves. There are in addition a number of situations in which the use of deadly force is permitted even though there is no official purpose to take life. In certain circumstances, deadly force can be used to defend oneself or others against the threat of death or serious injury or to prevent commission of a felony or the escape of a felon. The combination of another strongly supported value and the unavoidable necessity of risking life to protect that value excuses the homicide. If life is not taken intentionally, there is no criminal liability unless the actor’s conduct is culpable to the extent specified by the categories of unintentional criminal homicide, the least of which requires substantial negligence. Many unforeseen deaths that can be traced causally to the conduct of a particular person occur simply as accidents for which no one is criminally responsible.

Criminal homicide is everywhere divided into categories that reflect the historical distinction in English law between murder and manslaughter. American statutory formulations have varied the terminology and the precise classifications; many statutes create more than two forms of criminal homicide, for purposes of definition and/or punishment. These variations notwithstanding, it is usually possible to discern a category that corresponds to the common law crime of murder, the paradigm of which is a deliberate killing without legal justification or excuse, and a category that corresponds to the common law crime of manslaughter and comprises killings that either are committed in circumstances which substantially mitigate their intentional aspect or are not intentional. In common speech as well as in the law, murder refers to the most serious criminal homicides, and manslaughter to those that may be serious crimes for which a substantial penalty is imposed but lack the special gravity of murder.


The traditional definition of murder is that it is a homicide committed with ‘‘malice aforethought.’’ That phrase, as it developed in English law, was a technical term referring to the mental state of the actor or to the other equivalent circumstances that qualified a homicide as murder. It did not invariably require malice or forethought. While it is still common to use the phrase in connection with murder, it has no independent descriptive significance. In the common law, there was malice aforethought if the homicide was accompanied by (1) intention to kill; (2) intention to cause serious injury; (3) extreme recklessness or disregard of a very substantial risk of causing death; (4) commission or attempted commission of a felony; or (5) according to some authorities, resistance to a lawful arrest. Modern definitions of murder have clarified and in some respects limited these as elements of the crime of murder. In general, the distinguishing feature of the crime is an intent to kill or a disregard of so plain a risk of death to another that it is treated as the equivalent of an intent to kill.

Intention to Kill

All jurisdictions place the intentional killing of another without jurisdiction, excuse, or mitigating circumstances within the category of murder, as the most serious form of criminal homicide. While intentional killings may be classified further into subcategories of greater or lesser gravity, there is no controversy about their general classification as murder. Intent to kill has nothing to do with motive as such. While the circumstances that give rise to the intent may mitigate culpability, the law makes no differentiation between a killing with a benevolent motive, like euthanasia, and any other intentional killing.

Ambiguities in the general use of the concept of ‘‘intention’’ to describe conduct have caused trouble in its use to define murder. If the actor’s very purpose is to kill, there is no difficulty. It may be, however, that the death of another is an apparently necessary means to the accomplishment of his purpose but that he would be just as satisfied if it wee achieved otherwise. Or, he may be aware that a death is a substantially certain consequence of his conduct, without wanting or trying to bring it about. Courts have wrestled with the distinctions among such states of mind and sometimes offer elaborate analyses of them in the context of particular facts. While such efforts may help to explain the result based on those facts, they do not yield generalizations beyond the ordinary open use of the concept of intention. In general, if the actor is aware that the likelihood of a death resulting from his conduct goes beyond the level of risk to the level of certainty or near-certainty, the element of intent is satisfied. The availability of another category of murder based on extreme recklessness instead of intent helps to ease the burden of decision in borderline cases.

Since persons who intend to kill unlawfully are not likely to proclaim their intention, murder must often be established without explicit proof of intent to kill. The use of a deadly weapon is ordinarily sufficient to establish that element of the crime. While this result may be based on a ‘‘presumption’’ arising from use of a deadly weapon, the presumption amounts only to the usual inference that a person intends the ordinary and probable consequences of his actions. A killing may be murder even though the actor intended to kill someone other than the person who was the actual victim. Although the killing of that person was not intentional, it is enough that the actor acted with the intent to kill. His intent is sometimes said to be ‘‘transferred’’ to the actual killing.

As one of the most serious crimes, murder has historically been a capital offense. All cases of murder were capital offenses under the common law, which remained unchanged in England until 1957, when the class of capital murders was sharply limited; before then, capital punishment could be avoided only by the exercise of executive discretion to commute the sentence of death. In the United States, the Pennsylvania legislature in 1794 limited capital punishment by distinguishing between intentional killings that are ‘‘willful, deliberate or premeditated’’ and those that are not (Pa. Act of April 22, 1794, ch. 257, § 2, 3 Dallas 599). (The formula was later changed to ‘‘willful, deliberate and premeditated.’’) The former, along with a restricted category of felony murder, discussed below, and killing by poison or lying in wait, were labeled murder in the first degree and remained punishable by death. All other kinds of murder were designated murder in the second degree and were not capital offenses. This distinction and the ‘‘degree’’ labels were adopted elsewhere and continue to be widely used. While the term willful by itself does not add to the requirement of intent, the deliberation-premeditation formula calls attention to the difference between someone who kills ‘‘in cold blood,’’ fully aware of what he is doing and determined to bring about the result, and someone who acts intentionally but impulsively, without having turned the plan over in his mind. Courts have repeatedly observed that deliberation and premeditation require no particular period of reflection; a very short time before the plan is formed and, once formed, executed, is enough. For this reason and because it is so unclear what kind or quality of deliberation and premeditation is required, the formula has been criticized for giving juries power to dispense verdicts of different severity without any workable standard to guide them. As much criticized as it has been, and difficult as it has been to apply in close cases, the formula reflects a perceived difference of culpability in the paradigms.

Intention to Injure Seriously

The intention to injure that constituted one of the common law’s categories of malice aforethought was an intention to cause serious physical injury, stopping short of death itself. Provided that the intended injury is truly serious, so that an accidental death from an ordinary assault is not included, few homicides that fall within this category would not also fall within one of the other categories of murder. Death having in fact been the result, in most cases in which a jury is able to find the necessary intent to injure it will be able to find either an intent to kill or extreme disregard of a risk to life. One of the functions of this category of malice aforethought may indeed have been to relieve somewhat the burden of finding an intent specifically to kill rather than to inflict a serious injury.

The Model Penal Code eliminates intent to injure as a separate basis of liability for murder. The drafters concluded that proper cases for liability of this type will be included without it. The only clear case of murder under the common law that is excluded under the Code is one in which the actor inflicts serious injury while taking express precautions not to kill his victim, and the victim dies anyway. Such a case would in any event fall within some category of criminal homicide—manslaughter, if not murder. On the other hand, retention of the common law classification leaves the possibility that unless the degree of seriousness of the intended injury is emphasized, an unintentional killing not accompanied by the same culpability as an intentional killing will be treated in the same way. Some jurisdictions follow the lead of the Model Penal Code; many others retain this category of murder.

Extreme Recklessness

The common law recognized as the equivalent of an intent to kill an attitude of extreme recklessness toward the life of others. One whose conduct displayed plain disregard for a substantial, unjustified risk to human life was guilty of murder if his conduct caused a death. Various formulas have been used to describe this category of malice aforethought, including phases such as ‘‘a depraved mind regardless of human life,’’ ‘‘an abandoned and malignant heart,’’ and ‘‘a heart regardless of social duty and fatally bent on mischief.’’ Whatever formula is used, the key elements are that the actor’s conduct perceptibly creates a very large risk that someone will be killed, which he ignores without adequate justification. The risk must be large, and it must be evident; there must also not be circumstances that make it reasonable to impose such risk on others. It is not necessary that the actor be aware of the identity of the person or persons whose life he endangers or that he have any desire that they be killed. The Model Penal Code sums this up in a requirement of recklessness ‘‘under circumstances manifesting extreme indifference to the value of human life’’ (§ 210.2 (1)(b)).

The scope of this category of murder evidently depends considerably on how ‘‘extreme’’ the actor’s conduct has to be. Properly limited, the category includes only conduct about which it might be fairly said that the actor ‘‘as good as’’ intended to kill his victim and displayed the same unwillingness to prefer the life of another person to his own objectives. Examples of such conduct, which have been the basis of convictions for murder, are firing a gun into a moving vehicle or an occupied house, firing in the direction of a group of persons, and failing to feed an infant while knowing that it was starving to death. Expanded much beyond cases of this kind, the category might include conduct involving a high degree of carelessness or recklessness that is nevertheless distinct from an intent to kill and more properly included within some lesser category of homicide.

The question is occasionally raised whether the actor must be aware of the risk he creates, if it would be plain to an ordinary reasonable person. Unless the actor is subject to some personal disability that accounts for his lack of awareness, it is most unlikely that he will be unaware of, rather than simply indifferent to, a plain risk so extreme that murder is in issue. In such a case, the resolution will probably depend on the jurisdiction’s treatment of that kind of disability generally. If the disability is accepted as a defense or mitigation generally, then it will avoid the charge of murder; otherwise, the actor’s lack of awareness will not help him. Thus, for example, while the Model Penal Code’s formulation requires conscious disregard of the risk of death, one who was unaware of the risk because he was drunk could nevertheless be found guilty of murder, because the Code elsewhere provides that self-induced intoxication does not avoid a charge of recklessness as an element of an offense. Aside from special cases of this kind, it is probably safe to conclude that the extreme recklessness that characterizes this category of murder includes a realization of the risk. A lesser degree of risk, of which the actor might be unaware, would suffice for manslaughter but not murder.

Felony Murder

The common law crime of murder included a homicide committed by a person in the course of committing (or attempting to commit) a felony. The felon—and, according to the rules of accomplice liability, his accomplices—was guilty of murder even if he had no intent to kill or injure anyone and committed no act manifesting extreme recklessness toward human life. The origin of this doctrine may reflect the difficulty of proving specifically an intent to kill, in circumstances in which the intent to commit a felony may suggest a willingness to kill if necessary and other proof either way is lacking. Felonies under early English law were mostly violent crimes and were in any case punishable by death. An attempt to commit a felony was only a misdemeanor, however; the felony murder doctrine, which also applied to uncompleted felonies, did change the outcome if a homicide was committed during an unsuccessful attempt.

The number of felonies has increased dramatically under modern law. Statutory felonies include a large number of offenses that, however serious on other grounds, do not ordinarily pose great danger to life. Application of the felony murder doctrine to them distorts the concept of murder as a crime involving a serious direct attack on the value of human life. The explanation that the intent to commit the felony ‘‘supplies’’ the malice aforethought merely states the conclusion. So also, stretched to its logical limits, the felony-murder doctrine would make a felon guilty of murder even if the victim were killed by someone else trying to prevent the felony, provided it were found that the commission of the felony caused the death. In this way, it was occasionally held that when a policeman fired at felons and the bullet struck and killed a bystander, the felons were guilty of murder.

Far as such a death is from the intentional killing that is the paradigm of murder, one can perhaps understand the attitude that leads to the conclusion that the felon should be liable. If not for the felon’s conduct—the commission of the felony—the victim would not be dead, accidentally or not. Since in that sense the commission of the felony is the cause of death and the felon has in any case engaged in criminal conduct, it is easy to hold him responsible for the death as well. Even so, it is not appropriate to describe his conduct as murder if he has not engaged in conduct that seriously endangers life. Murder is not simply homicide, but homicide of a particularly culpable nature because it is accompanied by defined mental states; although willingness to commit a felony is itself culpable, it is not the same as, or equivalent to, the culpability that qualifies a homicide as murder.

While the doctrine of felony murder has sometimes been extended to cases very remote from an intentional killing, the courts and legislatures have quite generally adopted rules to restrict its scope. One restriction that responds to a large number of nonviolent statutory felonies is that the doctrine is applicable only if the underlying felony involves violence or danger to life. Sometimes it is required that the type of the underlying felony meet this requirement; or it may be enough if the commission of the felony in the particular circumstances is violent or dangerous. The first approach retains the felony murder doctrine on its own terms but confines it to a more limited group of felonies; to the same general effect are requirements that the felony have been a felony at common law or that it be malum in se. The second approach may create liability in a case not covered by the first; it looks in the direction of a displacement of felony murder by a different rationale based directly on the dangerousness of the actor’s conduct.

In many states that have more than one category of murder, the more serious category includes homicides committed in the course of one of a short list of particularly dangerous felonies: usually arson, rape, robbery, and burglary; commonly kidnapping; and sometimes one or two others. All other felony murders are in the less serious category. The Pennsylvania degree statute of 1794, referred to above, made this distinction; only homicides committed in the course of the first four mentioned crimes were murder in the first degree.

The nature of the underlying felony is restricted also by the requirement that it be ‘‘independent’’ of the homicide. Otherwise, every felonious assault from which death results might be prosecuted as murder, by operation of the felony-murder doctrine. Such an outcome would obliterate the common law difference between murder and manslaughter and would treat alike homicides of very different character and culpability. Even so, the requirement of independence has been rejected in a few jurisdictions, which presumably leave it to the good sense of the prosecutor not to reach an inappropriate result. The requirement does not apply if the person who is killed is someone other than the victim of the assault.

Another way of restricting felony murder places strong weight on the element of causation. Mere temporal conjunction of the felony and death has never been sufficient for felony murder; it is necessary at least that the death would not have occurred but for the felony. Some courts have explicitly required more than ‘‘but for’’ causation; the death must be a reasonably foreseeable, or natural and probable, consequence of the felony and must not be attributable primarily to a separate, intervening cause. Various ad hoc rules rejecting felony murder when someone other than the felon or an accomplice actually commits the homicide or when an accomplice is killed take a similar approach, although they refer to the party who kills or is killed rather than to causation as such.

The duration of the period during which the felony-murder doctrine applies is not uniformly defined. Once the felony is in progress, the doctrine certainly applies, but it is possible to end its application sooner or later after the felony is complete or has been abandoned, to include or exclude, in particular, flight from the scene of the felony. Some statutes explicitly include the period of flight. There is no clear general rule, the doctrine usually is applicable if the flight is continuous with the commission of the felony and if it cannot yet be said that the felony has succeeded or failed.

A more general attack on felony murder rejects it entirely and subsumes appropriate cases of homicide in the course of a felony under another category of murder. If a felon acting either with intent to kill or with extreme recklessness commits a homicide, then he is guilty of murder on that basis; the fact that the acts were committed in furtherance of a felony obviously does not count against liability. Reflecting the conclusion that if no element of that kind is present, then the felon’s liability for murder is gratuitous, the Model Penal Code and the statutes of a few states have eliminated the felony-murder doctrine. Elsewhere, there has been a partial displacement of the strict doctrine by allowance of an affirmative defense if the felon’s own conduct was not intended to and did not in any way endanger life. Of course, if the commission of a felony is itself deemed sufficient to satisfy the requirement of extreme recklessness (on the ground that a felony of that nature is always extremely dangerous to life), the concept of felony murder is reintroduced with the pretense of a different rationale. The Model Penal Code, for example, notwithstanding its strong criticism of the felony-murder doctrine, provides that recklessness and extreme indifference to the value of human life, which support liability for murder, are presumed if the actor is committing or is in flight after committing, one of half a dozen named violent felonies (§ 210.2(1)(b)). Some courts occasionally criticize the doctrine but preserve its force in particular cases by tenuous application of an alternative basis of liability to the specific facts. England, where the doctrine originated, abolished it by statute in 1957 (Homicide Act of 1957, 5 & 6 Eliz. 2, c. 11, § 1).

The uneven record of legislative and judicial efforts to limit or eliminate the felony-murder doctrine suggests strongly the central themes of the law of criminal homicide. When a death occurs and its occurrence can be attributed to the conduct of an identifiable person who is not blameless, there is a strong impulse to hold that person liable for the death, even if, from his point of view, the death should be viewed as accidental. The law not only reflects considered judgments about culpability; it also reflects an unconsidered effort to find an explanation and assign responsibility for an occurrence as disturbing to our sense of order as an unnatural death.

Resistance to a Lawful Arrest

Some of the older accounts of murder under the common law include resistance to a lawful arrest as a category of malice aforethought. Such a rule would impose strict liability for murder on a person whose resistance to a lawful arrest caused a death, even if it were accidental. It is now generally agreed that there is no such independent category of murder, although a statutory provision reflecting the traditional rule survives in a few states. A lawful arrest does not mitigate or excuse conduct in opposition to it, as might an unlawful application of similar physical force. Otherwise, homicide resulting from resistance to a lawful arrest if not treated differently from other homicide. Even in those states that have a special statutory provision, it is doubtful whether a wholly accidental death would be treated as murder if it did not also satisfy some other category of the crime. (England explicitly abolished this category of murder along with felony murder by means of the Homicide Act of 1957.)

Degrees of Murder

The distinction between first-degree and second-degree murder that the Pennsylvania legislature adopted in 1794 applied to intentional killings and felony murder. The statute referred explicitly to killings ‘‘by means of poison, or by lying in wait’’; but these were evidently intended simply as examples of ‘‘willful, deliberate, or premeditated killing.’’ Statutory provisions differentiating types of murder were subsequently enacted in other states. They typically followed the Pennsylvania formula (including references to poison and lying in wait, which sometimes took on a significance of their own) and occasionally made additional distinctions. As in Pennsylvania, the dominant purpose has been to restrict the imposition of the most severe penalty, whether capital punishment or the longest period of imprisonment. Among other circumstances that may qualify a homicide as first-degree, or capital, murder are the use of torture, destruction of or interference with the operation of a public conveyance, use of an explosive, murder for hire, and killing a public official or someone engaged in law enforcement.

Another approach is taken by the Model Penal Code, which rejects further classification of murder but specifies ‘‘aggravating circumstances’’ and ‘‘mitigating circumstances’’ to be taken into account in the determination of whether to impose capital punishment (§ 210.6). The aggravating circumstances include ones that have been used in statutory degree provisions, such as commission of specified violent felonies. They also include others which reflect a judgment that the special deterrent or preventive effect of the death penalty or an extreme measure of retribution is appropriate, as in the case of a defendant under sentence of imprisonment or previously convicted of murder or a violent felony, or where there has been more than one victim. Mitigating circumstances include aspects of the crime that lessen the defendant’s culpability as well as factors about the defendant himself, including his youth and lack of a criminal history. Capital punishment can be imposed only if at lest one aggravating circumstance, and no mitigating circumstance, is present. Decisions of the Supreme Court have imposed constitutional limitations on capital punishment, which appear to require an exercise of discretion in each case pursuant to legislatively prescribed standards. The approach of the Model Penal Code, which meets this test, has been widely adopted. The degree formula is still used to distinguish noncapital murders of unequal culpability; most often, as in the original Pennsylvania statute, the circumstances of first-degree murder are prescribed and other cases are grouped generally as second-degree murder.


As the common law developed, manslaughter became a residual category that included homicides lacking the very high degree of culpability that characterized the capital offense of murder but not so lacking in culpability as to be noncriminal altogether. The need for an intermediate category of this kind reflects the special significance given to the taking of human life; whereas the criminal law might disregard other kinds of harm that was not fully intentional, it could not disregard a homicide accompanied by any substantial degree of fault.

Two general groupings of manslaughter are distinguished in the common law, although they were treated as a single crime and were punishable similarly. They can be described generally as voluntary manslaughter and involuntary manslaughter, labels that are sometimes used in statutes to refer to separate crimes carrying different penalties, with voluntary manslaughter as the more serious offense. There is considerable variation among current statutory formulas, some of which continue to rely on the understandings of the common law and refer simply to manslaughter without defining it. It is still convenient to consider the crime according to the groupings of voluntary and involuntary manslaughter, those terms being used descriptively, whether or not there is explicit statutory differentiation.

Voluntary Manslaughter

The principal category of murder refers simply to a homicide committed with intent to kill, without taking account of circumstances that might mitigate culpability because they explain, and in some measure excuse, the actor’s state of mind. Voluntary manslaughter is an intentional homicide that would be murder but for the existence of such mitigating circumstances. It is commonly described as an intentional killing accompanied by additional factors that negate malice aforethought. Occasionally, voluntary manslaughter is described as a homicide committed in circumstances that overcome and eliminate an intention to kill. Such statements rely on a concept of intention that includes a measure of reflection; they should not be understood to require the killing be unintentional in the ordinary sense.

Most often, the factor that reduces homicide from murder to involuntary manslaughter is some act of the victim that prompts the intent to kill. The usual rule is that an intentional homicide is manslaughter if the actor was provoked to kill by an adequate provocation and acted while provoked, before sufficient time had passed for a reasonable person to have ‘‘cooled off.’’ It is not the provocative acts of the victim as such that reduce murder to manslaughter, but their effect on the actor. The most extreme provocation does not affect the result if it does not deprive the actor of self-control; one who responds to a provocation by cooling killing the person who provoked him is guilty of murder, not manslaughter.

Insisting that conduct be judged by the standard of a reasonable person, the law tended to develop rather rigid rules about the kinds of provocative act that were adequate; a violent battery by the victim and discovery of the victim committing adultery with one’s spouse were the paradigms of adequate provocation. Abuse by means of ‘‘mere words’’ was the paradigm of inadequate provocation. Other, less certain, categories were assault or a threat of assault on oneself or a battery or assault on a near relative. Whatever the nature of the provocation, it was not adequate if the actor responded by intentionally killing someone other than the source of the provocation. If, on the other hand, he directed his response against one whom he mistakenly believed to be the source of the provocation, or if accidentally or negligently he killed someone other than his intended victim, the provocation might be allowed. Rules of this kind are sometimes expressed as a general requirement that the homicidal response related to the nature and source of the provocation.

The cooling-off doctrine, as it is sometimes called, is yet another aspect of the requirement that provocation be adequate. A person is expected to regain control of himself within a reasonable period. Courts have sometimes applied this rule strictly and held that rage prolonged or renewed after enough time to cool off has elapsed does not reduce murder to manslaughter, whatever the actual provocation. Despite the argument that the passage of time and brooding over an injury might reduce rather than increase self-control, which may then be swept away by a slight reminder of the original injury, the evident judgment of the law was that only a sudden provocation adequate in itself should be taken into account.

The current direction of the law is to eliminate categorical restrictions of the provocation that may be adequate. The Model Penal Code eliminates all such restrictions and substitutes a general provision classifying as manslaughter ‘‘a homicide which would otherwise be murder [that] is committed under the influence of extreme mental or emotional disturbance for which there is reasonable explanation or excuse’’ (§ 210.3(1)(b)). This provision leaves it to the trier of fact to determine whether the actor’s loss of self-control is reasonably comprehensive, without prescribing in advance what sorts of provocation in what circumstances may meet that standard. A number of jurisdictions have adopted such an approach in whole or part, either by statute or judicial decision.

A distinct but related issue is whether the adequacy of provocation should be measured from the point of provocation should be measured from the point of view of an ‘‘ordinary reasonable person’’ or from the point of view of the actor, taking into account any idiosyncratic features he possesses. A defendant has sometimes claimed that provocation which would have been inadequate for an ordinary person was adequate in his case because of some factor peculiar to himself that made the provocative act unusually disturbing. Once again, the law has tended to relax its earlier insistence on an objective standard—without, however eliminating entirely the requirement that the actor’s behavior be objectively comprehensible. The Model Penal Code, for example, provides that the reasonableness of the actor’s explanation or excuse for his disturbance ‘‘shall be determined from the viewpoint of a person in the actor’s situation’’ (§ 210.3(1)(b)). The commentary to this provision explains that the actor’s physical handicaps are surely part of his ‘‘situation’’ but that idiosyncratic moral values are not; for the rest, the commentary observes, the reference to the actor’s situation is deliberately ambiguous and leaves the issue to the common sense of the finder of fact.

A provoked intentional killing is the most common example of voluntary manslaughter. There are a number of other situations in which an intentional killing is not altogether excused but the circumstances diminish culpability enough to remove it from the category of murder. In general, such situations are those in which a recognized basis for excusing the killing fails to apply fully because one of its elements is absent; nevertheless, the partial applicability of the excuse mitigates the killing. Thus, for example, a person who kills another in what he believes is necessary self-defense against a threat of death or serious injury is excused entirely if his belief is reasonable. If his belief is unreasonable, the defense of self-defense is not available. Even so, the fact that he acted in response to what he believed was a deadly threat distinguishes the crime from an intentional killing not prompted by such fear. His fear seems as appropriate a basis for mitigation as passion or rage caused by provocation.

Similarly, one who uses deadly force in defense against an actual threat of death or serious injury may not be excused entirely if he provoked the attack or if he did not retreat as required before using deadly force. One may use deadly force to protect another person or to prevent commission of a felony, in circumstances that make these defenses not fully available. In these and similar cases of an imperfect excuse, the intention to kill is in a significant sense responsive rather than original with the actor. That element contradicts the extreme denial of the value of human life that characterizes murder. England and a few jurisdictions in the United States have recognized the possibility that a person’s capacity to reflect and weigh the consequences of his conduct may be significantly less than normal, without being so abnormal that the defense of insanity is available. His ‘‘diminished capacity’’ may then provide a basis for reducing an intentional killing from murder to manslaughter. Even where this defense is recognized, it is allowed infrequently and in special circumstances only, lest all objective elements of the distinction between murder and voluntary manslaughter be swept away and replaced by an assessment of the actor’s subjective culpability.

Involuntary Manslaughter

As the name suggests, involuntary manslaughter comprises homicides that are not intentional and lack the special elements of culpability that qualify certain unintentional killings as murder but are nevertheless deemed too culpable to be excused entirely. The crime is recognized in all states in a variety of statutory formulations, which generally follow the common law pattern and may rely wholly on the common law definition. Whether or not it is explicitly differentiated from voluntary manslaughter by statute, involuntary manslaughter is regarded as a less serious offense and usually punished less severely.

A person whose criminal negligence causes the death of another is guilty of involuntary manslaughter. It is generally agreed that negligence sufficient for liability is considerably greater than what would suffice for civil or tort liability. Such negligence may be characterized simply as ‘‘criminal,’’ ‘‘gross,’’ or ‘‘culpable’’ negligence; as ‘‘recklessness’’; or as ‘‘reckless’’ or ‘‘wanton’’ carelessness. The central element is unjustified creation of a substantial risk of serious injury or death. Sometimes it is also required that the actor be aware of and disregard the risk, in which case the standard of culpability is more aptly described as recklessness than as negligence. The standard is measurably lower than the extreme recklessness that suffices for murder.

An alternative basis of liability for involuntary manslaughter under the common law and most statutory provisions is commission of an unlawful act or an unlawful omission from which death results. Although the unlawfulness of the conduct may be indicative of negligence, under this theory it is the unlawfulness, rather than the nature of the risk created by the conduct, that establishes liability. In principle, liability might extend to conduct that is unlawful but not criminal, but in practice, liability us usually restricted to conduct that is criminal (but not a felony that will support felony murder). Where vehicular homicide has not been made a separate offense, violation of a traffic regulation is a common example.

Frequently described as misdemeanor manslaughter, this form of criminal homicide has been criticized on the same grounds as felony murder and limited along the same lines. Paralleling the restriction of felony murder to violent felonies, misdemeanor manslaughter is sometimes limited to offenses that are malum in se, lest liability be extended to all the conduct that has been made a misdemeanor by statute. Moreover, the requirement of causation has been applied strictly, courts distinguishing between the illegal aspect of the conduct as a causal factor in the homicide, and merely an attendant circumstance of an accidental death. The tendency of the law, not always stated explicitly in the cases, is to confine misdemeanor manslaughter to situations in which the actor’s negligence provides a basis for liability, the illegal act having only evidentiary significance on that issue. Such a development reflects the same analysis that has led to the restriction or elimination of felony murder as a distinct category of that crime.

A homicide resulting from an unlawful battery or assault on the victim without intent to kill or injure seriously may be treated as manslaughter without express reliance on the misdemeanor manslaughter rule. The intention to injure the victim and the commission of an act to that end are evidently perceived, like criminal negligence, as a sufficient basis for liability if death results, without special emphasis on the illegality of the conduct. Since an unjustified attack is always at least a misdemeanor (malum in se), such cases might also be regarded as straightforward examples of misdemeanor manslaughter. (Even if, because of aggravating circumstances, the battery were felonious, the ‘‘independence’’ requirement would preclude application of the felonymurder doctrine.) The Model Penal Code, which rejects the misdemeanor manslaughter rule entirely, eliminates liability for manslaughter when death results accidentally from a battery.

Negligent or Vehicular Homicide

In much the way that the Pennsylvania degree formula differentiated types of murder in order to limit application of the death penalty, statutes in may jurisdictions provide for a lesser category of involuntary criminal homicide. Commonly called negligent homicide or something similar and treated as a separate offense, the category may also be distinguished simply as a lesser degree of manslaughter. A lower standard of culpability applies than that for manslaughter. In particular, recklessness or conscious disregard of the danger to others is not required. While negligence suffices, it is still more than is needed for civil liability. The precise standard of culpability both as set forth in a statute and elaborated by the courts is likely to depend significantly on the formula used to define involuntary manslaughter, with which it must be contrasted.

In some states, the lesser offense is made specifically applicable to motor-vehicle accidents and labeled ‘‘vehicular homicide.’’ Even when a high degree of negligence can be established, juries have frequently been unwilling to convict a driver of manslaughter. The large number of traffic fatalities, often occurring in accidents for which liability is uncertain, has evidently made it easier to perceive such deaths as an ordinary, random incident of driving and has diminished the need to resort to the criminal law for explanation. Reduction of the criminality and the penalty attached to the offense acknowledges these changed attitudes and has made application of some criminal sanction more likely.

Homicide Penalties

The decision of the Supreme Court in Coker v. Georgia, 433 U.S. 584 (1977) raised considerable doubt as to whether capital punishment is constitutionally permitted for any crime other than homicide. Those jurisdictions that retain capital punishment always include among capital crimes a category of murder, which may be narrowly restricted. The Supreme Court has indicated that, except perhaps in very special circumstances, the Constitution prohibits mandatory imposition of the death sentence. The decision whether to impose sentence of death is made by the judge and/or jury, pursuant to various statutory procedures that generally provide for full consideration of aggravating and mitigating factors.

Whether or not capital punishment is retained, murder is always regarded as one of the most serious offenses, for which (or for the most serious category of which) the law’s maximum penalty can be imposed. Most jurisdictions authorize a sentence for murder ranging up to life imprisonment, and a minimum sentence of imprisonment for a substantial number of years, commonly as many as ten or twenty. For the most serious category of murder, some jurisdictions provide a mandatory sentence of life imprisonment. Penalties for manslaughter vary widely. The maximum penalty may be as high as ten or twenty years’ imprisonment, and the minimum as little as one or two. If involuntary manslaughter is treated separately, the maximum penalty is less—usually not more than five years’ imprisonment. The penalty for negligent homicide or vehicular homicide usually does not exceed three years’ imprisonment.

The sentencing provisions of the Model Penal Code are representative of this general pattern. Murder, a felony of the first degree (§ 210.2(2)), is punishable (capital punishment aside) by imprisonment for a minimum of not less than one nor more than ten years and for a maximum of life. Manslaughter, a felony of the second degree (§ 210.3(2)), is punishable by imprisonment for a minimum of not less than one nor more than three years and for a maximum of ten years. Negligent homicide, a felony of the third degree (§ 210.4(2)), is punishable by imprisonment for a minimum of not less than one nor more than two years and for a maximum of five years.


The extent to which criminal homicide can be characterized as a single crime or family of crimes is indicated by the fact that the less serious categories are treated as lesser included offenses within the more serious. In a prosecution for first-degree murder, for example, the jury is likely to be instructed on second-degree murder, as well as voluntary manslaughter and even involuntary manslaughter, if any view of the evidence would support those verdicts. The taking of human life, as the harm to be avoided, rather than a common type or measure of culpability, is what binds the whole together.

That element has been critical in efforts to reform or rationalize homicide offenses according to general principles of the criminal law. Although criminal responsibility is thought not to be properly based on fortuities, whether of not death results from an act is often fortuitous from the point of view of the actor and may have large consequences because the severity of the penalty increases so dramatically if death does result. When the circumstances of a death do not allow one to regard it as an ordinary event in human experience, the need for explanation is strong and includes the assignment of blame if that is plausible.

The replacement of strict rules and categories, such as those that characterized voluntary manslaughter, with more general and open principles that refer directly to our primary concerns, may not further the purpose of rationalizing the law of homicide as much as we should like. The exercise of judgment or discretion is, in the end, guided by the same basic impulses as those that led to the more rigid structure. Thus, for example, despite insistence that the doctrine of felony murder is not consistent with basic premises about criminal responsibility, it persists in one form or another. Perhaps the most significant and constant thread in the long development of the law of homicide has been the progressive narrowing of the application of capital punishment. That has not been the product of greater understanding of the bases of liability for homicide so much as a drawing away from capital punishment as such.


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